This invention relates to resin molded stators, more particularly to resin molded stators excellent in crack resistance at the molded portions and in insulating properties of coils immediately after the molding of the molded coils and under high temperatures and moisture.
Recently, in order to improve properties and reliability of electric machines, or in order to conduct miniaturization and weight saving of electric machines or rationalization of production processes thereof, there have widely been employed processes for molding a part or whole of these machines by using various molding materials (e.g. U.S. Pat. Nos. 3,758,799, 4,128,527, etc.). These processes have also been applied to motors and those having armature coils molded by compression or transfer molding using various molding materials such as thermosetting resins, e.g. epoxy resins, polyester resins, polyimide resins, silicone resins, phenol-formaldehyde resins, etc. in place of treatment with varnishes are available commercially.
But motors wherein coil end portions of stators for motors, slot portions and terminal portions are molded into one piece by the processes as mentioned above are hardly available commercially. This is because there remain many problems to be solved such as in crack resistance of molded articles, insulating properties of molded coils, reliability of motors under high temperatures and high moisture, and the like.